Zinc Links in a Receptor-Kinase Complex

Association of the T cell coreceptors CD-4 and CD-8 with the cytoplasmic kinase Lck regulates T cell activation and maturation. Kim et al. have explored the requirement for zinc in this interaction and report that the metal ion acts as a clasp that stabilizes a receptor-Lck complex. Peptides corresponding to a short region of Lck and in either receptor's cytoplasmic tail were unordered, but the presence of zinc induced the synergistic mutual folding of the peptides. Protein modifications could unlatch the clasp and modulate receptor-Lck binding.